1. Field of the Disclosed Embodiments
This disclosure relates to systems and methods for employing millimeter wave (mmWave) transmitter/receivers (radios) for inter-processor or inter-core communication in multi-core systems.
2. Related Art
The wireless communication industry, more than a decade ago, began to focus on the mmWave region of the radio-frequency (RE) spectrum for wireless communication based on unique characteristics with regard to energy propagation for wireless transmissions in this region of the RE spectrum.
Wireless mmWave communications, particularly those in the 60 GHz frequency range, experience a high level of atmospheric RE energy absorption. Understanding that the transmitted RE energy in this frequency region would be quickly absorbed by oxygen molecules in the atmosphere over long distances, wireless technology developers began to focus on this characteristic as a benefit for certain applications.
Previously, the high levels of atmospheric absorption and resultant range limitations were viewed as rendering mmWave technologies unsuitable for certain wireless applications. That trend and thinking have reversed. There has emerged a need for short-range, focused transmission paths that can support high rates of data communication to a number of beneficial uses. Wireless mmWave communication technologies, and particularly 60 GHz mmWave communication systems, present a solution to meet the emerging need.
The unique characteristic of limited energy propagation in an oxygen atmosphere for transmissions in the mmWave region of the RF spectrum and the need, therefore, to provide directional transmission and reception for these communications presents significant benefits such as increased immunity to interference for transmitter/receiver systems in comparatively close proximity to one another. Transmitting in the mmWave region of the RE spectrum results in a fairly focused beam as compared to transmitting in lower frequency ranges. It is this pencil beam transmission capability combined with high energy absorption outside the narrow transmission beam that provides the unique ability to reuse a same frequency in a comparatively localized region thus making it possible to operate multiple transmitter and receiver combinations on the same frequency, or nearly the same frequency, in close proximity to one another with very low likelihood of interference.
Another benefit of the use of mmWave communication lies in the relationship between signal wavelength and antenna size. Transmitters and receivers operating in the mmWave region use high-gain antennas to focus as much of the transmitted signal as possible onto the receiving antenna, thereby overcoming the effects of atmospheric absorption in the pencil beam between the transmitter and the receiver. Those of skill in the art recognize that, with an increase in RF frequency, wavelength decreases. This makes it possible to produce required gains with smaller antennas. Thus, in mmWave communications, compact, low-cost antennas can be used to achieve a highly focused beam. This architecture results in the emissions from a mmWave radio via a high-gain/narrow beam antenna being very narrow and focused. Point-to-point radios should have highly directional antennas in order that all the transmitted energy is directed just at the intended recipient. Highly focused antennas minimize the possibility of interference and maximize performance.
The above advantages have now been recognized as a first generation of mmWave, such as 60 GHz, wireless communication systems is in the process of being standardized as, for example, the proposed IEEE 802.11ad/WiGig standard. A broad spectrum of products that support mmWave wireless communication are being developed and manufactured.
A large percentage of computing platforms today employ multi-core technologies. The term “multi-core systems” generally refers to a single computing platform with two or more independent processors, referred to as “cores.” It is these processors or “cores” that are the actual units that execute the various applications based on program instructions in the computing platforms. At a basic level, having multiple cores in a computing platform makes it possible for the computing platform to execute multiple individual instructions at the same time. This capability results in increasing overall speed for applications and programs that support parallel processing among the two or more cores. This benefit can be enhanced by increasing the number of cores in the computing platform.
In virtually all current implementations of multi-core computing systems, inter-core communication is achieved through wired busses and implemented in a specific memory scheme. FIG. 1 illustrates a typical conventional multiple core installation including wired interconnects for inter-core communication. As shown in FIG. 1, a typical inter-core communication scheme includes each of multiple CPU cores 110A-X, and associated Level 1 caches, being connected by individual wired busses 150A-X to a wired bus interface 130 having (1) X ports to accommodate the individual wired busses 150A-X, and (2) Level 2 caches.
As a number of cores and wired interconnects increases in multi-core systems, so to do difficulties associated with the use of wired interconnects. There are a number of factors that make the use of wired interconnects an increasing problem for multi-core systems.
Principal among the difficulties that make wired interconnects a problem is that, with the increasing numbers of cores in multi-core systems, the interconnect logic between the cores, e.g., the busses, becomes increasingly complex. This difficulty becomes particularly acute in instances where, before a multi-core system become commercially viable or available, it must undergo extensive and costly testing. This testing itself involves extensive time and effort in interconnecting the multiple cores for the sole purpose of testing the cores themselves and the inter-core communication between cores. This testing process is becoming even more complex as the cores themselves, and therefore inter-connects between those cores, become more complex. For low cost, low power and low rate multi-core systems, having a complex and costly wired interconnect scheme is undesirable.